The recovery of landfill gases including light hydrocarbons such as methane has become commonplace and is regulated under New Source Pollution Standards (NSPS). It used to be common to bum gasses vented from landfills. It is, however, becoming more common to use landfill gases to generate heat and/or electricity. Prior methods have resulted in increased costs and risks associated with managing gases and liquids in landfills.
Landfill leachate, the aqueous solution that accumulates at the bottom of landfills, also poses disposal and odor problems. One method for dealing with leachate odor problems that is gaining wide acceptance is to pump the leachate from the bottom to the top of the landfill to allow the leachate to percolate though the landfill where moisture and biological material in the leachate provide the foundation blocks (e.g., sources of moisture and nutrition) for microorganisms that will ultimately remediate and stabilize the landfill. The normal biological degradation of organic landfill materials can be dramatically accelerated by being able to cost effectively control the moisture and aerobic/anaerobic environments within and landfill resulting in the recycling or creation of more landfill airspace, thereby extending the useful landfill life.
The combination of leachate recirculation and gas extraction in landfills has created a problem with gas extraction, well flooding, fouling and effective control of the aerobic vs. anaerobic phases within a landfill. Prior attempts have resulted in systems that increase the overall costs of disposing of waste by as much as one hundred percent. In addition, prior methods introduced unnecessary risks associated with odor generation and liquid management. There is a need in the art for landfill gas extraction and leachate circulation that are easier and cheaper to construct while controlling the inner landfill environment more effectively. The invention is directed to this, as well as other, important ends.